What is safer? Headless administration of servers (linux) or GUI-driven local administration (windows server 2003)? Arguments for headless administration include:
Restricted Access to local utilities (if configured)
Few chances to compromise the server system through virus or trojan programs
You can check the arguments in the linux/windows security comparison at http://www.register.co.uk Register
Opponents claim better GUI support through windows 2003 administration programs.
An important point to watch is simply the question whether a server OS that is called secure can be administrated without breaking the security rules. If e.g. like in the old days of Windows NT the system is rated "C2" but only in a standalone (no network) mode then this is not a realistic way of running those systems and the rating is purely marketing.
The same goes for the tasks that require administration rights. If a system is called safe when running only regular user rights - what happens during administration when admin rights must be used?